$ rustc UnicodeTest.rs error[E0308]: mismatched types --> UnicodeTest.rs:12:32 | 12 | print!("{}", char::from_u32(i)); | -------------- ^ expected `u32`, found `isize` | | | arguments to this function are incorrect | note: associated function defined here --> /opt/local/libexec/rust/src/rustc-1.71.1-src/library/core/src/char/methods.rs:139:18 help: you can convert an `isize` to a `u32` and panic if the converted value doesn't fit | 12 | print!("{}", char::from_u32(i.try_into().unwrap())); | ++++++++++++++++++++ error[E0277]: `Option<char>` doesn't implement `std::fmt::Display` --> UnicodeTest.rs:12:17 | 12 | print!("{}", char::from_u32(i)); | ^^^^^^^^^^^^^^^^^ `Option<char>` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `Option<char>` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args` which comes from the expansion of the macro `print` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0308]: mismatched types --> UnicodeTest.rs:25:32 | 25 | print!("{}", char::from_u32(i)); | -------------- ^ expected `u32`, found `isize` | | | arguments to this function are incorrect | note: associated function defined here --> /opt/local/libexec/rust/src/rustc-1.71.1-src/library/core/src/char/methods.rs:139:18 help: you can convert an `isize` to a `u32` and panic if the converted value doesn't fit | 25 | print!("{}", char::from_u32(i.try_into().unwrap())); | ++++++++++++++++++++ error[E0277]: `Option<char>` doesn't implement `std::fmt::Display` --> UnicodeTest.rs:25:17 | 25 | print!("{}", char::from_u32(i)); | ^^^^^^^^^^^^^^^^^ `Option<char>` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `Option<char>` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args` which comes from the expansion of the macro `print` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0308]: mismatched types --> UnicodeTest.rs:37:32 | 37 | print!("{}", char::from_u32(i)); | -------------- ^ expected `u32`, found `isize` | | | arguments to this function are incorrect | note: associated function defined here --> /opt/local/libexec/rust/src/rustc-1.71.1-src/library/core/src/char/methods.rs:139:18 help: you can convert an `isize` to a `u32` and panic if the converted value doesn't fit | 37 | print!("{}", char::from_u32(i.try_into().unwrap())); | ++++++++++++++++++++ error[E0277]: `Option<char>` doesn't implement `std::fmt::Display` --> UnicodeTest.rs:37:17 | 37 | print!("{}", char::from_u32(i)); | ^^^^^^^^^^^^^^^^^ `Option<char>` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `Option<char>` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args` which comes from the expansion of the macro `print` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0308]: mismatched types --> UnicodeTest.rs:49:32 | 49 | print!("{}", char::from_u32(i)); | -------------- ^ expected `u32`, found `isize` | | | arguments to this function are incorrect | note: associated function defined here --> /opt/local/libexec/rust/src/rustc-1.71.1-src/library/core/src/char/methods.rs:139:18 help: you can convert an `isize` to a `u32` and panic if the converted value doesn't fit | 49 | print!("{}", char::from_u32(i.try_into().unwrap())); | ++++++++++++++++++++ error[E0277]: `Option<char>` doesn't implement `std::fmt::Display` --> UnicodeTest.rs:49:17 | 49 | print!("{}", char::from_u32(i)); | ^^^^^^^^^^^^^^^^^ `Option<char>` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `Option<char>` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args` which comes from the expansion of the macro `print` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0308]: mismatched types --> UnicodeTest.rs:62:32 | 62 | print!("{}", char::from_u32(i)); | -------------- ^ expected `u32`, found `isize` | | | arguments to this function are incorrect | note: associated function defined here --> /opt/local/libexec/rust/src/rustc-1.71.1-src/library/core/src/char/methods.rs:139:18 help: you can convert an `isize` to a `u32` and panic if the converted value doesn't fit | 62 | print!("{}", char::from_u32(i.try_into().unwrap())); | ++++++++++++++++++++ error[E0277]: `Option<char>` doesn't implement `std::fmt::Display` --> UnicodeTest.rs:62:17 | 62 | print!("{}", char::from_u32(i)); | ^^^^^^^^^^^^^^^^^ `Option<char>` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `Option<char>` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args` which comes from the expansion of the macro `print` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0308]: mismatched types --> UnicodeTest.rs:74:32 | 74 | print!("{}", char::from_u32(i)); | -------------- ^ expected `u32`, found `isize` | | | arguments to this function are incorrect | note: associated function defined here --> /opt/local/libexec/rust/src/rustc-1.71.1-src/library/core/src/char/methods.rs:139:18 help: you can convert an `isize` to a `u32` and panic if the converted value doesn't fit | 74 | print!("{}", char::from_u32(i.try_into().unwrap())); | ++++++++++++++++++++ error[E0277]: `Option<char>` doesn't implement `std::fmt::Display` --> UnicodeTest.rs:74:17 | 74 | print!("{}", char::from_u32(i)); | ^^^^^^^^^^^^^^^^^ `Option<char>` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `Option<char>` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args` which comes from the expansion of the macro `print` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0308]: mismatched types --> UnicodeTest.rs:86:32 | 86 | print!("{}", char::from_u32(i)); | -------------- ^ expected `u32`, found `isize` | | | arguments to this function are incorrect | note: associated function defined here --> /opt/local/libexec/rust/src/rustc-1.71.1-src/library/core/src/char/methods.rs:139:18 help: you can convert an `isize` to a `u32` and panic if the converted value doesn't fit | 86 | print!("{}", char::from_u32(i.try_into().unwrap())); | ++++++++++++++++++++ error[E0277]: `Option<char>` doesn't implement `std::fmt::Display` --> UnicodeTest.rs:86:17 | 86 | print!("{}", char::from_u32(i)); | ^^^^^^^^^^^^^^^^^ `Option<char>` cannot be formatted with the default formatter | = help: the trait `std::fmt::Display` is not implemented for `Option<char>` = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead = note: this error originates in the macro `$crate::format_args` which comes from the expansion of the macro `print` (in Nightly builds, run with -Z macro-backtrace for more info) error: aborting due to 14 previous errors Some errors have detailed explanations: E0277, E0308. For more information about an error, try `rustc --explain E0277`.